Stop mechanism for sewing machines



Aug. 5, 1941. MQsER 2,251,368

STOP MECHANISM FOR SEWING MACHINES 1 Filed Aug. 8, 19:59. 4 Sheets-Sheet 1 Aug. 5, 1941.

J. MOSER STOP MECHANISM FOR SEWING MACHINES Filed Aug. 8, 1939 4 Sheets-Sheet 2 was I INVENTOR.

L/0H/V MO5E/?' BY 6 ATTORNEY.

Aug. 5, 1941. os

STOP MECHANISM FOR SEWING- MACHINES Filed Aug. 8, 1939 4 Sheets-Sheet 5 6 7 I a a m r I\. m j m M w 1 7 M 9 00 7 w 8 z 7 y 4 a w, W m o m w \LI 1 v w 113 INVENTOR.

' OHN MOSER BY M ATTORNEY.

-Aug. 5, 1941. Mos 2,251,368

STOP MECHANISM FORSEWING MACHINES Filed Aug. 8, 1939 4 Sheets-Sheet 4 44a l I 160 L 146 129 f if: I @1 141 128 125 INVENTOR. 146

.domvMosER. BY

ATTORNEY.

Patented Aug. 5, 1941 Application August 8, 1939, Serial No. 288,943

4 27 Claims. (Ci. 112- -219) This invention relates toan automatic stop mechanism for sewing machines and has for an object to provide a mechanism for automatically stopping a sewing machine when either the bottom or top thread breaks or runs out.

Another object is to provide a stop mechanism which may be readily and conveniently actuated by the operator, as by means of a push button control or the like.

Another object is to provide a novel and improved mechanism of the above type which is adapted to be connected with the usual control elements of a standard sewing machine.

A further object is to provide an automatic stop mechanism for a sewing machine which may be readily applied to a standard sewing machine,

pulleys 20 are loosely mounted on a shaft 2 I, carried by the bracket I9, and are provided with a friction face 22, forming a clutch, which is adapted to frictionally drive the pulley I5.

In the embodiment shown, the clutch is controlled by means of a control arm 25, pivotally mounted on a bracket 26, which is attached to the underside of the table I8. The arm 25 carries a downwardly extending lever 21 which is provided with an adjustable screw 28 adapted to bear against a bearing surface at the axis of the pulleys 20 for holding the friction face 22 in driving engagement with the pulley I5 when the arm 25 is held down. When the arm is raised,

and which is of simple construction and is eiilcient and dependable in operation.

Various other objects and advantages will beapparent as the nature of the invention is more fully disclosed.

, Although the novel features which are believed to be characteristic of this invention are pointed out more particularly in the claims appended hereto, the invention itself may be better understood by referring to the following description, taken in connection with the accompanying drawings, in which a specific embodiment thereof has been set forth for purposes of illustration.

In the drawings,

Figure l is a front elevation of a sewing machine embodying the present invention;

Figure 2 is an end elevation thereof;

Figure 3 is a top plan view thereof;

Figure 4 is a perspective view of the automatic switch mechanism;

Figure 5 is a perspective view of the premer foot to be used in the machine of Figures 1 to 3;

Figure 6 is a longitudinal section through the presser foot of Figure 5;

Figure '7 is a schematic wiring diagram showing the electrical connections;

Figure 8 is a front elevation of a portion of the machine illustrating a further embodiment of the invention; and

Figure 9 is an end elevation of the mechanism shown in Figure 8.

Referring to the drawings more in detail, the embodiment of the invention shown in Figures 1 to 7 comprises a sewing machine head III having a presser foot bar I2 and a needle bar II driven by suitable drive mechanism, not shown, from a pulley I3 which is driven from a drive pulley I 5 by a belt I4. The sewing machine head is shown as mounted on a base or table I8 which is supported in any convenient manner. A bracket I9, 5 attached to the bottom .of said table I8, carries the drive pulley I5. The drive pulley I5 is driven from pulleys which may be actuated by a belt drive from a suitable motor (not shown). The

the lever 21 is moved to the left, as shown in Figure 1, and releases the driving pressure of the friction face 22 on the pulley I5. At the same time, a brake is applied to the pulley I5 by means of a lever 30 which is also attached to the arm 25 and is provided with an ear 3| which bears against a strip of friction material 32, such as felt or the like, and is adapted to hold the same in frictional engagement with the pulley I5. Consequently, when the arm 25 is raised, the clutch driving the pulley I5 is released and a brake is applied thereto for stopping the machine.

The drive pulley I5 and the appurtenant elements thereof, such as the pulleys 20, the clutch 22, the control arm 25, and the brake constitute, and are commonly termed in the art as, the transmission.

It is to be understood that the mechanism thus far described is of standard construction and only so much thereof has been set forth as is necessary to an understanding of the present invention. The details of the machine and of the drive may be varied in accordance with standard practice. In any case, however, the control arm 25 or equivalent mechanism is provided for starting or stopping the machine, either through a clutch mechanism or by direct control of the driving motor.

A will hereafter be more fully explained, the instant invention contemplates stopping the transmission when the needle thread breaks or becomes exhausted or when the bobbin thread breaks or becomes exhausted,

In accordance with the present invention, an electrically controlled lock and release are provided for the arm 25. Referring to Figures 1 and 2, this lock and release comprise a re-set lever 35 which is hinged at 36 to a bracket 31 attached to the underside of the table I8. The re-set lever extends to the front of the machine so as to be readily accessible to the operator and operates in a guide 38 which is also attached to the underside'of the table I8. The guide 38 is provided with bottom and top stop means 39 and 40, respectively, to limit the movement of the re-set lever 35.

" 55. The plate 5| is provided with an ear 56 having an aperture 51 in which the rod 46 slides. The ear 56 serves as a guide for the rod 46, while permitting relative movement between the rod 46 and arm 25 which are otherwise connected solely through the spring 53. The collar 54 provides means for adjusting the tension of the spring 53 as desired.

For normally holding the re-set lever 35 in its lower position so that tension is applied to the spring 53 for exerting a downward pull on the arm 25, there is provided a latch mechanism comprising a pawl 68 which is pivoted to the re-set lever 35 at 6| and is provided with an adjustable stop mechanism 62 which limits the outward movement of the pawl. A spring 63 normally holds the pawl inwardly, or to the left as seen in Figure 2. The pawl 68 is provided with an ear 64 which engages a retractable latch 65. The retractable latch 65 is operated by a solenoid or electromagnet 66 which is of standard construction and is arranged so that ener-, gization of the solenoid or electromagnet 66 retracts the latch 65 and releases the pawl 60, thereby permitting the re-set lever 35 to move upwardly and release the pull of the spring 58 on the arm 25. clutch drive and stops the sewing machine as above described. The sewing machine is again started by pressing the re-set lever 35 downwardly where it is automatically locked by the pawl 60, re-engaging the latch 65.

For energizing the solenoid 66 when the thread breaks or runs out, there is provided an automatic switch mechanism, shown more in detail in Figures 1 and 4. This switch mechanism comprises a bracket 10 which is attached to the sewing machine head It] by means of screws 1!. The bracket 10 carries an extension 12, having an upturned contact flange 13 thereon, forming one contact of the switch to be described. An electrical connection is made to this contact flange by means of a binding post 14. An insulating plate 15 is shown as attached to the bracket 10 by means of a screw 16. This plate 15 carries a pin 11 on which a contact arm 18 is pivoted. This contact arm 18 is provided at its end with a loop 19 through which the thread is passed in the manner to be described and may carry a weight 80 for causing the arm to drop and make electrical contact with the contact flange 13 when the tension of the thread is reduced. Obviously, spring means may be used for actuating the contact arm if desired. The spring means may supplement or replace the weight 80. Electrical connection may be made to the'arm 18 by means of a binding post 8| carried in the plate 15.

The thread 82 is passed from a spool 85 car- .ried on a post -'86-attached to the sewing ma-.

chine head l0, through a pair of tensioning devices 81 and 88, thence through a guide 89 to a needle 96 carried in the needle bar II. The tensioning devices 81 and 88 are disposed on opposite sides of the contact arm 18 so that The arm 25 then releases the the thread passes through the loop 19 of the arm 18 as it extends between the tensioning devices.

The lower tensioning device 86 may comprise the usual tensioning device of the sewing machine. This device applies a limitedamount of tension to provide a uniform thread feed. The upper tensioning device 81 may be adjusted to exert a drag adapted to hold the thread under sufllcient tension to ensure the proper operation of the arm 18 as will be described. The arrangement is such that,'when normal tension is applied to the thread as in stitching, the arm 18 is held upwardly, as shown in Figure 1, out of contact with the flange 13. When the tension on the thread is reduced, however, due for example'to breaking of the thread Or exhaustion of the bobbin as hereafter described, the arm 18 is released and is allowed to fall downwardly and make contact with the flange 13. The arm 18 acts to pull the thread back through the tensioning device 88, thereby providing sufllcient slack to allow the same to drop as above described. The upper tensioning device 81, however, prevents feed of the thread from the spool 85 except during the normal stitching operation.

It is to be understood that a particular type of thread-controlled switch has been shown as an example only. The details may, be varied as desired. The contact arm may, for example, bear against the thread and may be released in any convenient manner when the tension of! the thread is reduced.

In order to cause the above-described switch mechanism to be operated also when the bobbin thread runs out or breaks, a presser foot is provided which is attached to the presser foot bar l2 in the usual manner and is provided with the usual aperture 96 through which the needle passes. In accordance with one embodiment of the present invention, the presser foot 95 is provided with a knife blade 91 which is attached thereto by a screw 98. This knife blade rests in a groove 99 formed in the presser foot and may be adjusted as desired. The presser foot 95 is provided with a slot I00 which extends from the aperture 96 toward the rear of the presser foot, at least beneath the knife blade 91 so that, when stitches are skipped through failure of the bobbin thread the needle thread will be drawn under the presser foot with the goods and The slot I08 extends over the line of stitches.

so as to prevent the presser foot from engaging the same to hold the thread. Hence, the thread is pulled against the knife blade and severed when it is not held in the form of a stitch by the bobbin thread.

This embodiment is particularly adapted for use in a machine of the type in which the goods are pulled under tension from the point of stitching. In that case, the upper thread is pulled along with the goods until severed by the knife blade. In certain other types of machines, such as those in which the feed is accomplished only by the feed dogs, the knife blade may be omitted. In such machines, when stitches are skipped through failure of the bobbin thread the needle thread will pile up in the slot I80, thereby releasing the tension and permitting the switch arm 18 to make contact as above described. In certain cases, the lower tensioning device 88 may be omitted and the required drag may be applied by the upper device 81.

2,251,368 The electric circuit for operating the electromagnet 66, as shown in Figure '1, comprises a battery or other source of current I05 connected by a line I06 to a push button I01, which may be mounted on the front table I3, as shownin Figure 1, and by a line I to the binding post ill of the contact arm I8. From the push button I0I a connection is made by a line I03 to the bracket 31. A similar connection to the'bracket 31 is made from the binding post I4 of'the contact flange I3 by a line IIO. Connection is made through the re-set lever 35 and pawl 00 to the held down by the latch 35 and pawl 30, as above described.

If the bobbin thread runs out or breaks, the

top thread instead of forming a stitch may be pulled along on the top of the goods and brought In either case, the arm I8 is actuated to stop latch 55 to which the solenoid 65 is grounded by a lead III. A line .I I2 connects the other side of the solenoid 66 to a return line II3 connected to the battery I05. Lines I00 and H0 may be extended for multiple operation of other .ma--

chines.

In Figure 7 there is shown a belI H0 and a signal light III which are connected to be actuated when the automatic switch is closed by the arm I8. The bell H6 and the signal light I" are connected by a line II8 to the binding post It of the automatic switch and through a switch I20 and a line I2I to the return line I I3.

Operation In the above-described mechanism, the pulleys 20 are continuously driven and the connection to the sewing machine mechanism is made or broken by the action of the arm 25 which, in its lower position, applies pressure to hold the friction face 22 of the pulleys 20 in engagement with the pulley I and, in its upper position, releases the pulley I5 and applies a brake thereto as above described. To start the machine, the thread 02 is passed between the tensioning devices BI and 05 and through the loop III of the contact arm The re-set lever 35 is then pushed down- I5. wardly to cause the pawl 30 to engage and be secured beneath the latch 55. Moving the reset lever 35 places the spring 53 under tension and thereby pulls the arm 25 downwardly for starting the machine. During the stitching operation, the thread 02 remains under tension and holds the contact arm I0 out of contact with the contact flange I3 of the automatic switch. When the thread breaks, however, or the tension is otherwise reduced, the contact arm I5 is released and drops to make contact with the flange I3, thereby completing the circuit to the solenoid 55 andto the bell H5 and the signal light III, as shown in Figure 7. The solenoid, being energized, retracts the latch 55 and releases the pawl 55, permitting the re-set lever to move upwardly, thereby releasing the spring tension and permitting the arm 25 to move upwardly for stopping the machine. It is to be understood, of course, that this operation takes place practically instantaneously. When the pawl is released, the circuit to the solenoid is broken at the latch 55.

If it is desired to manually stop the machine, the operator merely presses the button I01,

thereby completing the circuit through the solenoid 55 and actuating the same above-described.

In restarting the machine, the re-set lever may in the manner be held down until the thread is brought under tension so as 'to prevent the automatic switch from again stopping the machine. The lever may be held down to a point such that contact with the latch 05 is broken, if desired, so as to reduce current consumption. As soon as the machine has begun to stitch, the lever will be the machine.

It is to be understood, of course, that various changes may be made in the above-described mechanism. The re-set lever 35 may, of course, be mounted in various positions and may be connected to the arm 25 in various ways.

A further embodiment of. the invention is shown in Figures 8 and 9. In this embodiment, the re-set lever 35 is replaced by a rock shaft I25 which is mounted beneath the table I0 by means of brackets I25. This rock shaft extends to the front of the machine and is provided with a control lever IIi'I. It also carries a bracket I20 vwhich is adjustably secured thereto by a set screw I29 and supports a rod I30, which is likewise adjustably secured by a set screw I3l. The rod I50 pivotally carries a pawl I60 which is similar to the pawl 50 described above. This pawl is pivoted to the rod I30 by a pin I32 and is provided with stops I33 which limit the move ment thereof. A spring I34 normally holds the pawl in latching engagement with the latch 65 of the solenoid 05.

The rock shaft I25 also carries a bracket I40 which is adjustably secured by a set screw III and carries a rod M2. The rod I42 carries a plate I43 to which a rod I IB is attached. The rod I00 corresponds to the rod 40 of Figures 1 to 3 and is connected to the arm 25 by means of the spring 53 and collar 50, as above described.

The operation of this form of the invention is similar to that described above except that the rock shaft I25 is allowed to rotate when the pawl I55 is released. The rotation of this rock shaft I25, in a counter-clockwise direction as seen in Figure 8, releases the tension on the spring 53 and stops the machine. Rotation in the opposite direction, which is caused by manually operating the lever IN for re-setting the mechanism, serves to apply tension to the spring 53 and thereby actuates the arm 25 for starting the machine.

It is to be understood that the mechanism may take various forms. Two different embodiments have been shown and described above for purposes of illustration only. The position and arrangement of the electrically con-trolled latch and of the re-set lever or rock shaft controlling the arm 25 may be varied as desired so as to adapt the mechanism for attachment to existing machines. Obviously, in the construction of a new machine in which it is not necessary to make use of exist- 1 ing parts, the electromagnetic latch mechanism tuated when the contact arm 18 makes contact with the flange 13.

Certain specific terms have been used herein for convenience in referring to the various details of the invention. These terms, however, are to be given as broad an interpretation as the art will permit. The scope of the invention is to be limited only in accordance with the following claims.

I claim:

1. In a sewing machine having a presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, means normally holding said thread under a predetermined tension, control means connected to interrupt said' transmission from driving said driven means and thereby stopping the machine, and means responsive to a variation in the tension of said thread from normal for actuating said control means, said presser foot having means associated therewith for varying the tension on the needle thread when the normal stitching operation is interrupted by failure of the bobbin thread.

2. In a sewing machine having a presser foot,

a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, means normally holding said thread under a predetermined tension, control means connected to interrupt said transmission from driving said driven means and thereby stopping the machine, and means responsive to a reduction in tension of said thread to actuate said control means, said presser foot having means associated therewith for releasing the tension on the needle thread when the normal stitching operation is in-, terrupted by failure of the bobbin thread.

3. In a sewing machine having a presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, means maintaining said thread under a predetermined tension during the stitching operation, a thread-controlled switch comprising a. contact arm engaging said thread and held open by the tension of said thread, means whereby said arm closes said switch when the tension of said thread is released, and means controlled by said switch for interrupting said transmission from driving said driven means and thereby stopping said machine, said presser foot having means associated therewith for releasing the tension on the needle thread when the normal stitching operation is interrupted by failure of the bobbin thread.

4. In a sewing machine having a reciprocating needle, a bobbin, and a presser foot, driven means to actuate said needle, a transmission to drive said driven means, means to feed a tin-cad to said' needle for stitching, control means connected to interrupt said transmission from driving said driven means and thereby stopping said machine,

means responsive to a reduction in tension of said thread produced by severing the same for actuating the control means, said presser foot having means associated therewith for severing said thread when the normal stitching operation is interrupted by failure of the bobbin thread.

5. In a sewing machine having a reciprocating needle, a bobbin, and a presser foot, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, control means connected to interrupt said transmission from driving said driven means and thereby stopping said machine, means responsive to a reduction in tension of said thread produced by severing the same for actuating the control means,said presser foot having a knife edge associated therewith for severing said thread when the thread is pulled along with the goods due to failure of the bobbin thread.

6. In a sewing machine having a presser foot, a reciprocating needle, mechanical drive means for said needle, clutch means for controlling said mechanical drive means, a pivoted arm actuating said clutch means, means normally holding said arm in operating position, a latch mechanism for said arm, electrically operated release means for said latch mechanism, means to feed a thread to said needle for stitching, means holding said thread under a predetermined tension during normal stitching operations, and a thread-controlled switch actuated when the tension of said thread is reduced, said switch being connected to actuate said electrically operated release means for stopping said machine, said presser foot having means associated therewith for releasing the tension on the needle thread when the normal stitching operation is interrupted by failure of the bobbin thread.

7. In a sewing machine having a reciprocating needle, mechanical drive means for said needle, clutch means for controlling said mechanical drive means, a pivoted arm actuating said clutch means, a re-set lever, spring means interconnecting said re-set lever and said arm, a pawl and a latch normally latching said re-set lever in driving position, electromagnetic means releasing said latch for stopping said machine, and threadcontrolled means actuating said electromagnetic means.

8. In a sewing machine having a reciprocating needle, mechanical drive means for said needle, clutch means for controlling said mechanical drive means, a pivoted arm actuating said clutch means, a re-set lever, spring means interconnecting said re-set lever and said arm, a pawl and a latch normally latching said re-set lever in driving position, electromagnetic means releasing said latchfor stopping said machine, and threadcontrolled means controlled by the tension of the thread for actuating said electromagnetic means when the tension of the thread is reduced by breakage of the thread or interruption of the normal stitching operation.

9. In a sewing machine having a reciprocating needle, mechanical drive means for said needle, clutch means for controlling said mechanical drive means, a pivoted arm actuating said clutch means, a re-set lever, spring means interconnecting said re-set lever and said arm, a pawl and a latch normally latching said re-set lever in driving position, electromagnetic means releasing said latch for stopping said machine, threadcontrolled means actuating said electromagnetic means, and means de-energizing said electromagnetic means when said re-set lever has been actuated to stop the machine.

10. In a sewing machine having a reciprocating needle, mechanical drive means for said needle, clutch means for controlling said mechanical drive means, a pivoted arm actuating said clutch means, a re-set lever, spring means interconnecting said re-set lever and said arm. a pawl and a latch normally latching said re-set lever in driving position, electromagnetic means releasing said latch for stopping said machine, and thread-controlled means actuating said electromagnetic means, said pawl and latch being connected'in circuit with said electromagnetic means whereby the circuit thereto is broken by the release of said pawl.

11. In a sewing machine, a presser foot having an aperture through which a. needle passes for stitching, a knife edge spaced from said aperture, and a slot extending from said aperture beneath said knife edge to cause the thread to be severed thereby when stitches are. skipped through failure of the bobbin thread.

12. A presser foot for a sewing machine, said presser foot having an aperture through which a needle passes for stitching, a slot extending rearwardly from said aperture, and a knife blade mounted over said slot to engage and sever a thread when stitches are skipped through failure of the bobbin thread.

13. A presser foot for a sewing machine, said presser foot having an aperture through which a needle passes for stitching, a slot extending rearwardly from said aperture, a knife blade mounted over said slot to engage and sever a thread when stitches are skipped through failure of the bobbin thread, and means permitting adjustment of said blade relative to said slot to effect the desired operating characteristics.

14. In a sewing machine having a reciprocating needle, a bobbin, and a presser foot, drive means for said needle, means to feed a thread to said needle for stitching, contro1 means connected to interrupt said drive means for stopping said machine, and means responsive to a reduction in tension of said thread for actuating the control means, said presser foothaving means associated therewith for releasing the tension on said thread when the normal stitching operation is interrupted by failure of the bobbin thread.

15. In a sewing machine having a presser foot, a reciprocating needle, drive means for said needle, means to feed a thread to said needle for stitching, a thread-actuated switch comprising a contact member and an arm normally making contact therewith, a tensioning device engaging said thread in advance of said arm to apply sufficient tension for holding said arm in open contact position during normal stitching, said arm being released by a reduction in thread tension caused by interruption of the stitching operation, and means controlled by said switch for interrupting said drive means andstopping the machine when said arm is released, said presser foot having means associated therewith for releasing the tension on the needle thread when the normal stitching operation is interrupted by failure of the bobbin thread.

16. In a sewing machine having a bobbin, a presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, a pair of spaced threadtensioning devices, a thread-controlled switch comprising a contact arm engaging said thread between said thread-tensioning devices and held open by the tension of said thread, means whereby said arm closes said switch when the tension of said thread is released, and means controlled by said switch for interrupting said transmission from driving said driven means and thereby stopping said machine, said presser foot having means associated therewith for releasing the tension on said thread when the stitching operation is interrupted by failure of the bobbin thread.

17. In a sewing machine having a bobbin, a presser foot, a reciprocating needle, driven means to actuate said needle, a transmisision to drive said driven means, means to feed a thread to said needle for stitching, a thread-controlled switch comprising a contact arm engaging said thread, a thread-tensioning device to exert a drag adapted to hold the thread under sufficient tension to hold said contact arm in open position, means whereby said arm closes said switch when the tension of said thread is released, and means controlled by said switch for interrupting said transmission from driving said driven means and thereby stopping said machine, said presser foot having means associated therewith for releasing the tension on said thread when the stitching operation is interrupted by failure or the bobbin thread.

18. In a sewing machine having a bobbin, a

presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, a thread-controlled switch comprising a contact arm engaging said thread, a thread-tensioning device disposed above said contact arm to exert a drag adapted to hold the thread under sufiicient tension to hold said contact arm in open position, a threadtensioning device disposed beneath said contact arm to provide a uniform thread feed, means whereby said arm closes said switch when the tension of said thread is released, and means controlled by said switch for interrupting said transmission from driving said driven means and thereby stopping said machine, said presser foot having means associated therewith for releasing the tension on said thread when the stitching operation is interrupted by failure of the bobbin thread.

19. In a sewing machine having a bobbin, a presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, a pair of spaced threadtensioning devices, a thread-controlled switch comprising a contact arm engaging said thread between said thread-tensioning devices and held open by the tension of said thread, means whereby said arm closes said switch when the tension of said thread is released, and means controlled by said switch for interrupting said transmission from driving said driven means and thereby stopping said machine, said presser foot having an apperture through which the needle passes and a slot extending from said aperture to the rear of said presser foot to avoid engaging and holding the thread when the stitch has been interrupted by failure of the bobbin thread.

20. In a sewing machine having a bobbin, a presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching; a thread-controlled switch comprising a contact arm engaging said thread, a thread-tensioning device to exert a drag adapted to hold the thread under sumcient tension to hold said contact arm in open position, means whereby said arm closes said switch when the tension of said thread is released, and means controlled by said switch for interrupting said transmission from driving said driven means and thereby stopping said machine, said presser foot having an aperture through which the needle passes and a slot extending from said aperture to the rear of said presser foot to avoid engaging and holding the thread when the stitch has been interrupted by failure of the bobbin thread.

21. In a sewing machine having a bobbin, a presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, a thread-controlled switch comprising a contact arm engaging said thread,

a thread-tensioning device disposed above said said machine, said presser foot having an aperture through which the needle passes and a slot extending from said aperture to the rear of said presser foot to avoid engaging and holding the thread when the stitch has been interrupted by failure of the bobbin thread. I

22. In a sewing machine having a bobbin, a

presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, a pair of spaced thread-tensioning devices, a thread-controlled switch comprising a contact arm engaging said thread between said thread-tensioning devices and held open by the tension of said thread, means whereby said arm closes said switch when the tension of said thread is released, and means controlled by said switch for interrupting said transmission from driving said driven means and thereby stopping said machine, said presser foot having an aperture through which the needle passes for stitching, a knife edge spaced from said aperture, and a slot extending from said aperture beneath said knife edge to cause the thread to be severed thereby when pulled along with the goods under said presser foot.

23. In a sewing machine having a bobbin, a

. presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, a thread-controlled switch comprising a contact arm engaging said thread, a thread-tensioning device to exert a drag adapted to hold the thread under suflicient tensionto hold said contract arm in open posi-' tion, means whereby said arm closes said switch when the tension of said thread is released, and means controlled by said switch for interrupting said transmission from driving said driven means and thereby stopping said machine, said presser foot having an aperture through which the needle passes for stitching, a knife edge spaced from said'aperture, and a slot extending from said aperture beneath said knife edge to cause the thread to be severed thereby when pulled along with the goods under said presser foot.

24. In a sewing machine having a bobbin, a presser foot, a reciprocating needle, driven means to actuate said needle, a transmission to drive said driven means, means to feed a thread to said needle for stitching, a thread-controlled switch comprising a contact arm engaging said thread, a thread-tensioning device disposed above said contact arm to exert a drag adapted to hold the thread under suflicient tension to hold said contact arm in open position, a thread-tensioning device disposed beneath said contact arm to provide a uniform thread feed, means whereby said arm closes said switch when the tension of said thread is released, and means controlled by said switch for interrupting said transmission from driving said driven means and thereby stop-,- ping said machine, said presser foot having an aperture through which a needle passes for stitching, a knife edge spaced from said aperture, and a slot extending from said aperture beneath said knife edge to cause the thread to be severed thereby when pulled along with the goods under said presser foot.

25. In a sewing machine having a reciprocating needle, mechanical drive means for said needle, clutch means for controlling said mechanical drive means, a pivoted arm actuating said clutch means, a re-set lever, a pair of plates on opposite sides of said arm and secured together to constitute a clamp, one of said plates having an apertured ear, a rod carried by said re-set lever and adapted to slide in said apertured ear, an adjustable collar carried by said rod, spring means interconnecting said collar and clamp, a pawl and a latch normally latching said re-set lever in driving position, electromagnetic means releasing said latch for stopping said machine, and threadcontrolled means controlled by the tension of the thread for actuating said electromagnetic means when the tension of the thread is reduced by breakage of the thread or interruption of the normal stitching operation.

26. In'a sewing machine having a reciprocating needle, mechanical drive means for said needle, clutch means for controlling said mechanical drive means, a pivoted arm actuating said clutch means, a rock shaft constituting a re-set lever, spring means interconnecting said re-set lever and said arm, a pawl and a latch normally latching said re-set lever in driving position, electromagnetic means releasing said latch for stopping said machine, and thread-controlled means controlled by the tension of the thread for actuating said electromagnetic means when the tension of the thread is reduced by breakage of the thread or interruption of the normal stitching operation.

2'7. In a sewing machine having a reciprocating needle, mechanical drive means for said needle, clutch means for controlling said mechanical drive means, a pivoted arm actuating said clutch means, a rock shaft constituting a re-set lever, a pair of plates on opposite sides of said arm and secured together to constitute a clamp, one of said plates having an apertured ear, a rod interconnected to said rock shaft and adapted to slide in said apertured ear, an adjustable collar carried by said rod, spring means interconnecting said collar and clamp, a pawl and a latch normally latching said re-set lever in driving position, electromagnetic means releasing said latch for stopping said machine, and thread-controlled means controlled by the tension of the thread for actuating said electromagnetic means when the tension of the thread is reduced by breakage of the thread or interruption of the normal stitching operation.

JOHN MOSER. 

